Parameter schema - ADOS Documentation

A plugin declares parameters under gcs.contributes.parameters[] (or nested inside a settings section). The GCS renders each as a native, dark-themed control, validates and clamps the committed value against the schema, and writes it to the binding you name. No iframe, no custom form code. A parameter has three parts:

- key: standoff_distance_m     # the config key the value is written under
  schema: { ... }              # the JSON-Schema data contract (what is valid)
  ui: { ... }                  # how it renders (widget, label, grouping)
  binding: plugin.config       # where the committed value is written

schema is the only required part beyond key. A missing or malformed schema drops the parameter at parse time (with a console warning); the rest of the manifest still loads.

`schema` — the data contract

schema is a Draft-07 JSON-Schema subset, deliberately scoped to what a drone-plugin parameter needs. Unknown keywords are ignored (forward-compatible), never an error.

Field	Type	Applies to	Notes
`type`	enum	all	`number`, `integer`, `boolean`, or `string`. Required.
`minimum`	number	number, integer	Inclusive lower bound.
`maximum`	number	number, integer	Inclusive upper bound. Must be `>= minimum`.
`step`	number	number, integer	Quantization / UI step. Must be positive.
`enum`	array	any scalar	Allowed values. When present, the value must be one of these. Pairs with the `enum` widget.
`pattern`	string	string	Regex source applied to string values. Must be a valid regex.
`default`	scalar	all	Applied when no stored value exists. Must itself be valid against the schema.

Validation and clamping. On every commit the host validates the value against the schema. Numbers are clamped to [minimum, maximum] and quantized to step; an integer is rounded. A string is checked against pattern. An enum value must be a member. An invalid value is rejected and the control reverts; a clampable value is clamped silently.

# An integer with bounds and a step
- key: max_targets
  schema:
    type: integer
    minimum: 1
    maximum: 16
    step: 1
    default: 4

# A pattern-validated string
- key: camera_name
  schema:
    type: string
    pattern: "^[a-zA-Z0-9_-]{1,32}$"
    default: "front"

# An enum (string members)
- key: follow_mode
  schema:
    type: string
    enum: ["chase", "orbit", "lead"]
    default: "chase"

integer is a schema type, not a widget. Both number and integer render with the number (or range) widget; integer adds the round-to-whole rule on commit.

`ui` — the presentation layer

ui never affects validation. It only controls how a parameter is shown and grouped.

Field	Type	Notes
`widget`	enum	The control to render. Inferred from `schema.type` when omitted; `range`, `model`, `model_upload` are always explicit.
`label`	string	The control label. Defaults to `key`.
`group`	string	Section grouping in the rendered panel.
`help`	string	Helper text under the control.
`visible_if`	object	Conditional reveal: `{ key, equals }`. Shows the control only when another parameter’s committed value equals `equals`.
`task`	string	For `model` / `model_upload`: the vision task the picker lists (`detection`, `reid`, `depth`).
`order`	number	Sort hint within a group.

Widgets

Widget	Renders	Default for
`number`	A numeric input that clamps and quantizes on commit.	`type: number` / `integer`
`range`	A slider between `minimum` and `maximum` stepping by `step`, with a live value readout.	(always explicit)
`boolean`	A toggle.	`type: boolean`
`enum`	A dropdown of the `enum` members, mapping the chosen string back to the typed value.	a schema with `enum`
`string`	A text input validated against `pattern`.	`type: string`
`model`	The board-filtered model picker bound to the engine’s active detector.	(always explicit)
`model_upload`	The model picker with upload enabled.	(always explicit)
`group`	A grouping marker (rare; prefer `ui.group` on each field).	(always explicit)

When ui.widget is omitted, the host infers: an enum schema becomes the enum widget, a boolean becomes boolean, a number/integer becomes number, and everything else becomes string.

Grouping and conditional reveal

Parameters are grouped by ui.group (groups order by first appearance, controls within a group by ui.order then declaration order). A control with visible_if shows only when the referenced parameter’s committed value matches.

contributes:
  parameters:
    - key: vio_enabled
      schema: { type: boolean, default: false }
      ui:
        widget: boolean
        label: "Enable VIO"
        group: "Navigation"

    # Only shown when vio_enabled is true
    - key: vio_backend
      schema:
        type: string
        enum: ["openvins", "vins_fusion"]
        default: "openvins"
      ui:
        widget: enum
        label: "VIO backend"
        group: "Navigation"
        visible_if: { key: vio_enabled, equals: true }

`binding` — where the value is written

The binding field routes the committed value. It defaults to plugin.config when absent.

Binding	Writes to	Read-back
`plugin.config`	The per-drone plugin config, over the LAN agent (local-first).	The agent exposes a config write but no config read, so the GCS seeds from the schema default and badges it “Default — not read from drone” until a value is committed this session.
`engine.detector`	The shared, engine-wide vision detector. Every vision consumer on that drone shares one detector.	The model picker owns the write and reports the new active model back, so the form tracks the live detector.
`agent.config`	A whitelisted system config key on the agent.	Read-only on this surface; its write router is a separate surface.

# Default: per-drone plugin config
- key: standoff_distance_m
  schema: { type: number, minimum: 2, maximum: 60, step: 0.5, default: 8 }
  ui: { widget: range, label: "Standoff distance" }
  binding: plugin.config

# A whitelisted system key, shown read-only here
- key: video_bitrate_kbps
  schema: { type: integer, minimum: 500, maximum: 20000, default: 4000 }
  ui: { widget: number, label: "Video bitrate" }
  binding: agent.config

On a plugin.config commit the host writes optimistically and rolls the control back if the agent does not accept the write, so the surface never shows a value the agent rejected. Because there is no config read-back, a freshly-loaded plugin.config control shows the schema default until the operator commits a value.

The `model` parameter — switch the vision detector

A model (or model_upload) parameter binds to engine.detector and renders the board-filtered model picker. Selecting a model switches the drone’s active vision detector engine-wide; every vision consumer on that drone then runs against the new model.

gcs:
  permissions:
    - id: ui.slot.node-detail-tab
    - id: telemetry.subscribe
  contributes:
    # Register the models the picker can offer (per-board variants).
    models:
      - id: coco-yolov8n
        task: detection
        board_variants:
          - board_match: "rk3588"
            runtime: "rknn"
            input: "640x640"
            min_tops: 3
            source: "https://example.com/models/coco-yolov8n-rk3588.rknn"
            sha256: "0000000000000000000000000000000000000000000000000000000000000000"
          - board_match: "generic-arm64"
            runtime: "onnx"
            input: "640x640"
            source: "https://example.com/models/coco-yolov8n.onnx"
            sha256: "0000000000000000000000000000000000000000000000000000000000000000"
    # A model parameter that lets the operator switch the active detector.
    parameters:
      - key: detector
        schema:
          type: string
          default: "coco-yolov8n"
        ui:
          widget: model              # render the model picker
          label: "Detector model"
          task: detection            # the picker lists detection models
          group: "Vision"
        binding: engine.detector     # switch the engine-wide detector

When the operator picks a model, the picker writes the engine-wide detector on the agent directly and reports the new active id back, so no second write happens and there is no optimistic rollback for this widget. Use model_upload instead of model when you want the operator to be able to upload their own model file.

A model widget needs a drone context to write to. On a detached preview (no selected drone) it falls back to a read-only display of the current value rather than rendering a picker with nowhere to write.

Full worked example

A small follow-behavior plugin’s parameter block, mixing a range, a toggle, a conditional enum, and a model switch:

gcs:
  permissions:
    - id: ui.slot.settings-section
    - id: ui.slot.node-detail-tab
    - id: command.send
  contributes:
    settings:
      - id: follow-tuning
        title: "Follow tuning"
        icon: "sliders"
        parameters:
          - key: standoff_distance_m
            schema: { type: number, minimum: 2, maximum: 60, step: 0.5, default: 8 }
            ui: { widget: range, label: "Standoff distance", help: "Meters behind the subject." }
          - key: standoff_height_m
            schema: { type: number, minimum: 2, maximum: 40, step: 0.5, default: 6 }
            ui: { widget: range, label: "Standoff height" }
          - key: gimbal_track
            schema: { type: boolean, default: true }
            ui: { widget: boolean, label: "Point gimbal at subject" }
          - key: lost_behavior
            schema: { type: string, enum: ["hover", "rth"], default: "hover" }
            ui: { widget: enum, label: "On lost", visible_if: { key: gimbal_track, equals: true } }
    models:
      - id: coco-yolov8n
        task: detection
        board_variants:
          - board_match: "generic-arm64"
            runtime: "onnx"
            input: "640x640"
            source: "https://example.com/models/coco-yolov8n.onnx"
            sha256: "0000000000000000000000000000000000000000000000000000000000000000"
    parameters:
      - key: detector
        schema: { type: string, default: "coco-yolov8n" }
        ui: { widget: model, label: "Detector model", task: detection }
        binding: engine.detector

​schema — the data contract

​ui — the presentation layer

​Widgets

​Grouping and conditional reveal

​binding — where the value is written

​The model parameter — switch the vision detector

​Full worked example

​See also

`schema` — the data contract

`ui` — the presentation layer

Widgets

Grouping and conditional reveal

`binding` — where the value is written

The `model` parameter — switch the vision detector

Full worked example

See also